An assembly having a bearing with an axis of rotation, and a fibre-based sensor for sensing strain or temperature of the bearing is disclosed. The sensor extends in a direction parallel to the axis of rotation. An aircraft system is disclosed including a wheel supported on an axle by a first bearing and a second bearing. The system further includes a first fibre optic sensor for sensing a strain or temperature of the first bearing, a second fibre optic sensor for sensing a strain or temperature of the second bearing, and an interrogator to analyse optical signals from the sensors to determine differences in the strains or temperatures of the first bearing and the second bearing.

A system for sensing microbends and micro-deformations in three-dimensional space is based upon a distributed length optical fiber formed to include a group of offset cores disposed in a spiral configuration along the length of the fiber, each core including a fiber Bragg grating that exhibits the same Bragg wavelength. A micro-scale local deformation of the multicore fiber produces a local shift in the Bragg wavelength, where the use of multiple cores allows for a complete micro-scale modeling of the local deformation. Sequential probing of each core allows for optical frequency domain reflectometry (OFDR) allows for reconstruction of a given three-dimensional shape, delineating location and size of various microbends and micro-deformations.

A fuel gauging sensing device for a fuel tank for aircrafts includes an optical fiber harness along the internal surface of the tank, a master optical controller connected to a first terminal of the optical fiber harness, a slave optical controller connected to a second terminal of the optical fiber harness, wherein the optical fiber harness includes Fiber Bragg Grating (FBG) sensors spaced in the optical fiber harness between 1 mm and 25 mm to provide temperature gradients inside the tank and wherein the master and slave optical controllers are configured to obtain the fuel gauging of the tank based on the output from the FBG sensors.

An optical fiber includes multiple optical waveguides configured in the fiber. An interferometric measurement system mitigates or compensates for the errors imposed by differences in a shape sensing optical fiber's response to temperature and strain. A 3-D shape and/or position are calculated from a set of distributed strain measurements acquired for a multi-core optical shape sensing fiber that compensates for these non-linear errors using one or more additional cores in the multicore fiber that react differently to temperature changes than the existing cores.

A method includes collecting spectral data from fiber Bragg grating sensors distributed at locations along a fiber optic component positioned along a streamer; and analyzing the spectral data to produce measurements of bend of an axis of the streamer proximate the locations. A streamer monitoring system includes: a fiber optic component positioned along a streamer; a plurality of fiber Bragg grating sensors distributed at locations along the fiber optic component; a light source optically coupled to the fiber optic component and configured to interrogate the fiber Bragg grating sensors; a photodetector optically coupled to the fiber optic component and configured to collect spectral data from the interrogated fiber Bragg grating sensors; and a spectral analyzer in communication with the photodetector and configured to analyze the spectral data to produce measurements of bend of an axis of the streamer proximate the locations along the fiber optic component.

The present disclosure relates to an arrangement (100) for obtaining a quantity related to a temperature along a part of an optical fibre (110). The arrangement comprises a light emitter (120) arranged to emit light into the optical fibre (110). The optical fibre is at at least one location along said part of the optical fibre provided with a Fibre Bragg Gratings, FBGs (111, 112, 113), wherein the FBGs are arranged to reflect light within a predetermined wavelength range. The arrangement further comprises a detector (160) arranged to receive and detect the reflected light, a first optical shutter (130) arranged in the optical path after the light emitter. The first optical shutter is arranged to be opened and closed in order to let the emitted light through and into the optical fibre (110), a second optical shutter (150) arranged to be opened and closed in order to let the reflected light through, and an optical circulator (140) having a first, a second and a third port. The optical circulator is operatively connected to the first optical shutter (130) at the first port, to the part of the optical fibre provided with the FBGs (111, 112) at the second port, and to the second optical shutter (150) at the third port. A control unit (180) is arranged to control the first optical shutter (130) and the second optical shutter (150). The control unit (180) is arranged to coordinate the timing of the opening of the first optical shutter (130) and the second optical shutter (150), respectively.

A sensor device for measuring a temperature in a photovoltaic laminate structure and a sensor system comprising such a sensor device is provided. The sensor device includes a capillary for being embedded in the laminate structure between two layers thereof, a medium arranged within the capillary, and an optical fiber extending through the capillary and surrounded by the medium. At least a portion of the optical fiber has temperature-dependent transmission characteristics.

A sensor apparatus is provided in which both an optical interrogator and an optical waveguide are embedded in the same component made of fiber-reinforced plastic. The optical interrogator and the optical waveguide thus form a unit with the component made of fiber-reinforced plastic, in which they are embedded. The optical interrogator and the optical waveguide are arranged in this case protected in the same component made of fiber-reinforced plastic. The optical waveguide does not have to be led out of this component and into the interrogator. The risk of damage to the optical waveguide is thus significantly reduced.

A method and apparatus for inscribing a Bragg grating in an optical waveguide, comprising: providing electromagnetic radiation from an ultrashort pulse duration laser, wherein the electromagnetic radiation has a pulse duration of less than or equal to 5 picoseconds, and wherein the wavelength of the electromagnetic radiation has a characteristic wavelength in the wavelength range from 150 nanometers (nm) to 2.0 microns (.Math.m); providing cylindrical focusing optics corrected for spherical aberration; providing a diffractive optical element that when exposed to the focused ultrashort laser pulse, creates an interference pattern on the optical waveguide, wherein the irradiation step comprises irradiating a surface of the diffractive optical element with the focused electromagnetic radiation, the electromagnetic radiation incident on the optical waveguide, from the diffractive optical element, being sufficiently intense to cause the permanent change in the index of refraction in the core of the optical waveguide.

There is provided a system for determining multiple baselines for detecting events in a conduit. The system comprises an optical fiber interrogator for interrogating optical fiber; and one or more processors communicative with the optical fiber interrogator and memory having stored thereon computer program code configured, when executed by the one or more processors, to cause the one or more processors to perform a method. The method comprises, for each of multiple channels of the conduit, each channel comprising a portion of the conduit: obtaining phase data for the channel, the phase data being obtained by causing the optical fiber interrogator to interrogate optical fiber positioned alongside the conduit; and determining one or more baselines from the phase data. As a result, events in the conduit may be detected with fewer false positives.